Development of multilayer Hydroxyapatite - Ag/TiN-Ti coatings deposited by radio frequency magnetron sputtering with potential application in the biomedical field

Abstract

The use of composite coatings is emerging as a great alternative to conventional coatings, allowing the combination of different superficial properties that are widely desired in surgical implants, such as osteointegration and bactericidal character, and cannot be provided by one material alone. In the present investigation the effect of the incorporation of a TiN-Ti intermediate bilayer on the chemical composition, structure, morphology, roughness, residual stresses and adhesion of a multi-layer Hydroxyapatite (HA)-Ag coating deposited on Ti-6Al-4V by magnetron sputtering was evaluated. Additionally, the cytotoxicity of the developed system was evaluated by in vitro tests. According to the results obtained, a decrease in the Ca/P ratio from 1.85 to 1.74 was obtained through the deposition of an HA-Ag system on the intermediate bilayer, and the crystallinity of the developed coating was favored. The multi-layer structure was effectively observed by field emission scanning electron microscopy, where it was possible to identify each of the HA, Ag, TiN and Ti layers. Meanwhile, an increase of 7% in crystallite size, a decrease of 36% in residual stresses and an increase of 32% in adhesion were registered for this composite coating compared to the free intermediate bilayer system. Finally, biological evaluation allowed the non-cytotoxic character of the deposited coatings to be confirmed.